package com.vernon.webspider.core.util;

import java.util.concurrent.ExecutorService;
import java.util.concurrent.ThreadFactory;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.atomic.AtomicInteger;

/**
 * 线程相关的Util函数集合
 *
 * @author Vernon.Chen
 * @date 2012-8-6
 */
public class ThreadUtil {

    /**
     * sleep等待,忽略InterruptedException.
     *
     * @param millis 等待时间,单位毫秒
     */
    public static void sleep(long millis) {
        try {
            Thread.sleep(millis);
        } catch (InterruptedException ignored) {
        }
    }

    /**
     * 按照ExecutorService JavaDoc示例代码编写的Graceful Shutdown方法.
     * 先使用shutdown尝试执行所有任务.
     * 超时后调用shutdownNow取消在workQueue中Pending的任务,并中断所有阻塞函数.
     * 另对在shutdown时线程本身被调用中断做了处理.
     *
     * @param pool
     * @param shutdownTimeout
     * @param shutdownNowTimeout
     * @param timeUnit
     */
    public static void gracefulShutdown(ExecutorService pool, int shutdownTimeout, int shutdownNowTimeout,
                                        TimeUnit timeUnit) {
        pool.shutdown(); // Disable new tasks from being submitted
        try {
            if (!pool.awaitTermination(shutdownTimeout, timeUnit)) {
                pool.shutdownNow(); // Cancel currently executing tasks
                if (!pool.awaitTermination(shutdownNowTimeout, timeUnit)) {
                    System.err.println("Pool did not terminate");
                }
            }
        } catch (InterruptedException ie) {
            pool.shutdownNow();
            Thread.currentThread().interrupt();
        }
    }

    /**
     * 直接调用shutdownNow的方法.
     *
     * @param pool
     * @param timeout
     * @param timeUnit
     */
    public static void normalShutdown(ExecutorService pool, int timeout, TimeUnit timeUnit) {
        try {
            pool.shutdownNow();
            if (!pool.awaitTermination(timeout, timeUnit)) {
                System.err.println("Pool did not terminate");
            }
        } catch (InterruptedException ie) {
            Thread.currentThread().interrupt();
        }
    }

    /**
     * 自定义ThreadFactory,可定制线程池的名称.
     */
    public static class CustomizableThreadFactory
            implements ThreadFactory {

        private final String namePrefix;
        private final AtomicInteger threadNumber = new AtomicInteger(1);

        public CustomizableThreadFactory(String namePrefix) {
            this.namePrefix = namePrefix + "-";
        }

        @Override
        public Thread newThread(Runnable r) {
            return new Thread(r, namePrefix + threadNumber.getAndIncrement());
        }
    }
}
